Machine tool control



Nov. 27, 1945. c. JOHNSON MACHINE TOOL CONTROL Filed Nov. 30, 1944INVENTOR. CLARENCE JOHNSON A TTORNEY Fae. 3

Patented Nov. 27, 1945 MACHINE TOOL CONTROL Clarence Johnson, SouthEuclid, Ohio, assignor to Bailey Meter Company, a corporation ofDelaware Application November 30, 1944, Serial No. 565,868

lCl. 82-14) 6 Claims.

This invention relates to duplicators or contour control for controllingthe operation of a material forming machine so that a work piece isformed to a contour or configuration determined by a template, patternor cam.

In accordance with my invention the template or cam for producing thedesired configuration on the work piece is scanned by a tracerregulating a jet of fluid from a nozzle or the discharge of fluid to theatmosphere from a valve. Variations in the shape of the template causecorresponding changes in the rate of fluid discharged from the nozzle orvalve, which variations are then used to control the relativepositioning of the tool and work piece.

Further, in accordance with my invention, the

changes in fluid pressure control the relative positioning of the tooland work piece through a hydraulic relay and servomotor to the end thatample power is available for accurately positioning the tool relative tothe work piece, or vice versa.

Obviously a duplicator or contour control of the type forming thesubject matter of my invention may be employed with material formingmachines or machine tools of various types, such as milling machines,lathes, slotters, planers, die sinking machines, and other machines inwhich the relative speed between the tool and work may be suitablycontrolled. By way of example I illustrate and will describe myinvention as applied to metal working vertical boring mills. Furtherapplications and modifications of my invention will be readily apparent.

In the drawing:

Fig. 1 is a somewhat diagrammatic side elevation of a portion of avertical boring mill to which my invention has been applied.

Fig. 2 is a transfer valve arrangement of Fig. 1.

Figs. 3 and 4 are examples of contour surfaces.

Fig. 5 is an. enlarged section taken through a portion of Fig. 4 alongthe line 5-5 in the direction of the arrows.

Fig. 6 is an enlarged section of a portion of Fig. 5 showing a machiningoperation,

In the past certain types of jobs have had to be handled on verticalmilling machines at relatively slow speed. Many of these jobs I can nowaccomplish with decided advantage in a vertical boring mill embodying myinvention. Preferably I utilize a single point cutting tool whichremains in a. fixed or stationary position and relative to which Irotate and otherwise move the work piece. The use of a single pointcutting tool provides numerous advantages, some of which will bementioned, while others will be apparent.

Throughout the specification and in the claims to follow I haveindicated that the workpiece is formed to correspond to the profile orshape of a master template or cam. By such language I do not intend toimply that the workpiece is brought to the exact shape of the master,but, as will be evident to those familiar with the art, the master willbe formed so that the ultimate shape of the work piece produced is thatdesired, and that therefore the shape of the work piece may differ fromthat of the master by the amount of angularity, etc., in the mechanism.Furthermore, I use the terms contour, profile, shape and the like in abroad sense, and not with any limiting distinction between the profileof a two-dimensional silhouette or the surface configuration of a bodyfor example. In general, the pattern dictates the desired shape of theworkpiece. I use profile and contour interchangeably. The pattern hasthe desired shape, although it is not necessarily the exact shape.

By strict definition one might be led to believe that profile is onlythe edge shape of a twodimensional silhouette for example. Usually it isspoken of as the edge shape of a thin plate template, although such atemplate is a threedimensional object. Usually contour is the surfaceconfiguration, or at least of a portion of the surface of athree-dimensional object. Applicant intends to make clear that inspeaking of profile or contour he means the forming of a workpiece to ashape as dictated by that of a template or pattern, and without anyspecific or limiting meaning being given to the terms profile andcontour.

The pattern or template has a shape corresponding to the desired path ofmovement of the tool or of the work to produce the desired finishedworkpiece. By corresponding is meant that not only is the pattern ortemplate the same shape as the desired workpiece either in greater orsmaller proportion thereto; but also the pattern or template may be inany desired distorted shape to compensate for characteristics of themachine. While the pattern or template must correspond to the desiredworkpiece, it is not necessarily identical in contour, and therefore theterm correspond implies that the pattern or template is purposelydesigned to result in the desired contour of the workpiece to beproduced.

Referring now to Fig. 1, I show my invention applied to a verticalboring mill having a table I positionable in either direction along asingle path on suitable ways (not shown). For positioning the table I Iprovide a hydraulic servomotor comprising a. cylinder 2 and piston 3.The cylinder 2 is rigidly mounted, while the piston 3 is arranged toposition the table I through the agency of a piston rod 4.

Mounted on the carriage I is a rotatable work holder 5 in which isfastened a workpiece 8. The holder 5 is normally rotated at a uniformspeed in common manner. The workpiece 6 (through movement of the tableI) is positioned in one direction or the other relative to the fixedcutting tool I. As so far described, the cutting tool I would cut acircular groove or depression in the upper surface of the workpiece 6and the diameter or such a cut would be determined by the right or leftmovement of the table I relative to the cutting tool I. A particularfeature of the present invention is for cutting spiral cuts, or inmachining irregular shaped gasket surfaces and the like.

In Figs. 3 and 4 I illustrate some of the irregular gasket shapes towhich I refer. For example, Fig. 3 represents an elliptical gasketsurface of a hand hole plate. Fig. 4 illustrates the irregular gasketsurface between the body and the head of a pressure chamber. Fig. 5illustrating a portion of a section through the mating gasket surfacesof Fig. 4. It is to this latter problem in particular that I will.direct my description.

Assuming now that the workpiece 6 is the lower portion of the assemblyof Fig. 5, to have a gasket surface prepared thereon of the generaloutline indicated in Fig. 4. Preferably such a gasket surface is at twoelevations or of the tongue and groove type wherein the gasket material8 is confined on three sides against the pressure acting on the fourthside. Furthermore, it is frequently desired to have surfaces finished towhat is commonly termed a phonograph finish comprising a surface ofconcentric r spiral groove to more readily grip a gasket againstrelatively high pressure.

Assume that the workpiece 6 of Fig. 1 is the lower portion 6 of theassembly in Fig. 5. The machined surfaces 9, III, II (Fig. are to beproduced on the workpiece 6 (Fig. l). Preferably these surfaces 9 and IIare to be of the phonograph finish type, whereas the surface III is tobe asmooth finished surface (Fig. 6). The original casting or roughworkpiece may have an unmachined surface 9A, IDA and HA.

Referring now to Fig. 1, it is apparent that ii, with the workpiece 6rotating, the tool I is fed downwardly it will cut a circular groove inthe top surface of the workpiece 6. To have the cut follow an outline,such as diagrammatically indicated at Fig. 4, it is necessary tosimultaneously move the table and work piece 6, to the right or leftrelative to the stationary tool 1. This is accomplished through theagency of the servomotor 2, 3 by means of a combinationpneumatichydraulic control which I will now describe.

At I2 I indicate a template or pattern having a configuration conformingto the general outline of Fig. 4 to be reproduced as a gasket surface onthe workpiece 6 tioned the contour or shape of the pattern I2 does notnecessarily match exactly the shape to be reproduced, but is so formedas to result in the proper shaping of the workpiece B. Preferably thepattern I2 is fixed with reference to the As previously men tool I andis rotated at a speed the same and in synchonism with the rotatingworkpiece 6. Inasmuch as this is accomplished through the ordinarygearing of the boring mill it is not necessary to explain in detail.

I provide a tracer assembly I3 having a tracer arm I4 adapted to scanthe pattern I2. Such a tracer assembly may be of the type disclosed inmy copending application, Serial No. 524,707. Air under pressure fromany convenient source is passed through a pressure regulator II and anorifice I6 to a pipe I I connected with the tracer assembly I3. As theair discharges from the tracer I3 to the atmosphere the pressure in thepipe I1 between the orifice I6 and the tracer assembly I3 will vary andsuch controlled air pressure representative of changes in contour of thepattern I2 is efl'ectlve upon a bellows III of a pilot valve assemblyIS. The pilot valve assembly I9 may be of the type disclosed in mycopending application above referred to.

I show an oil pump 20 driven by a moto 2| and drawing its supply of oilfrom a sump 22. Oil under pressure is supplied the pilot valve I! by thepump 20 through a pipe 23. From the pilot valve I9 oil is supplied toone end or the other of the servo-motor 2, 3 through the pipes 24 or 25.Drainage from the pilot I9 is returned to the sump 22 through a pipe 26.

If the configuration of the pattern I2 is a circle then there will be auniform pressure contact or deflection of the tracer arm I4 against theperiphery of the template I2 determining a uniform bleed of air to theatmosphere from the pipe I'I. Under this condition a constant airpressure, of some predetermined value, will exist within the bellows I8and the movable element of the relay valve I9 will be in a position tolock the pipes 24, 25 against admission or discharge of 40 oil fromopposite sides of 'the piston 3 in the cylinder 2. Thus the piston 3would remain stationary and the work 6 would not move toward the rightor toward the left on the drawing relative to the cutting tool I. Thecutting tool I would thus describe a circle on the rotating workpiece 6.If, however, the periphery of the template or pattern I2 is other than acircle, then as it rotates past the tracer arm I4 the said tracer armwill be deflected more or less with a resultant increase or decrease inthe bleed to atmosphere of air from the pip II. The result will be aninflow or outflow of oil at opposite sides of the piston 3 with amovement of the table I and work piece 8 to the right or to the leftrelative to the cutting tool I. Such movement of the table I, carryingthe tracer assembly I3, will follow up the deflection of the tracer armI4 and tend to stop further movement of the piston 3. Thus a continuousfollow-up is provided through actual movement of the table I in properdirection.

Under the conditions so far explained, the tool I would follow a path onthe work 6 conforming in general to the configuration of Fig. 4, butafter one complete revolution of the workpiece 6 the tool 'I wouldcontinue in the same path without additional cutting of material fromthe surface 9A or the surface IIA. It is, however. necessary to have thetool I out different paths for each revolution of the workpiece 6, orotherwise there would be no progressive machining across the workpiece 6to form the desired surfaces 9, III, II. Thus upon each revolution ofthe workpiece 8 the tool must describe a new path parallel to the firstcutting path, Or else preferably the entire cut must be a distortedspiral in nature.

- the sump 22.

If the cutting tool I is properly shaped and the transverse progressivemovement of the workpiece 6 relative to the tool I is properly adjusted,

the machined surface II will be substantially smooth. In many instances,however, it is desira'ble to have the surfaces 9, II (Fig. 6) aphonograph finish for better gripping of the gasket material, and thismay be accomplished through proper grinding of the tool shape and properlead of the spiral of its travel. Thus the magnitude of the hills andvalleys of the surface II and spacing of the cycle may be predetermined.I will now explain that feature of my invention which produces aprogressive movement of the table I and workpiece 8 transversely of thetool I while the workpieceis rotating. This to accomplish the spiral orphonograph cutting to progress the tool across the surface to bemachined as the work 6 is rotated.

Mounted on and carried by the table I I provide aservo-motor having acylinder 21 and piston 28 for positioning a slide 29 along ways 30relative to an adjustable stop 3|. The tracer assembly I3 is mounted onand positioned by the slide 29 on the table I.

Oil under pressure is supplied from the pump 28through a pipe 32, avalve 33, and a pipe 34 to the right-hand end of the cylinder 21. Oilfrom the left-hand end of the cylinder 21 is bled through a pipe 35, athrottle valve 36, a control valve 31, the pipe 38, valve 33 and a pipe39 to Depending upon the opening of the hand regulated valve 36 thepiston 28 will move continuously from the right-hand end of the cylinder21 toward the left-hand end. The speed of such movement depending uponthe throttling of the bleed valve 36.

As the piston 28 slowly moves toward the left on the drawing, the tracerarm ll contacting the pattern I2 is continuously and uniformly defiectedtoward the right. This produces a continuous predetermined pressurecondition within the pipe II and bellows I8 resulting in a uniformcontinuous movement of the piston 3 toward the right, thus traveling thetable I and workpiece 6 toward the right. Such table travel acts as afollow-up on the tracer I3 in an attempt to restore the pressureconditions within the bellows I8 and stop movement of the piston 3. Atthe same time this continuous uniform movement of the work 6 toward theright means that as the work 6 revolves the stationary tool I woulddescribe a spiral out upon the surface II or 9 if the configuration ofthe pattern I2 is a circle. With the pattern I2 shaped to conform to thedesired configuration of Fig. 4, for example, the pattern shapeadditionally influences the tracer arm It in positioning the table Irelative to the tool I.

The resulting action is that the surfaces 9A and HA will be machined tothe general configuration of Fig. 4 in a phonograph finish, as indicatedat 9 and I I, and such continued movement of the table I toward theright will continue until the left-hand end of the slide 29 engages thestop 3| whereafter continued rotation of the work 6 results in the toolI repeating its last cutting path.

Hand adjustment of the throttle valve 33 bleeding oil from the left-handend of the cylinder 21 determines the speed of travel of the piston 28toward the left in the cylinder 21, and thus the pitch or lead of thegrooves on a surface such as I I.

In Fig. 2 I show the alternate position of the valves 33, 31 for rapidreturn of the piston 28 toward the right in the cylinder 21. In theposition shown in Fig. 2 the throttle valve 36 is Suitable and ordinaryvalving means may be provided in connection with the servo-motor 2, 3tfor rapid traverse of the piston 3 in either direcion.

In Fig. 6 I indicate the possibility of simultaneously cutting with aplurality of single point tools I, IA. Thus to produce the machinedsurfaces 9, I8, II from the cast or rough initial surfaces 9A, IDA, HA Iprovide properly spaced single point tools 1, 1A. In Fig. 6 the tools I,IA are relatively cutting in the direction of the arrows through generalmovement of the table I toward the right. The tool I has produced aportion of the surface II shown in solid line and the tool IA is justready to begin producing the finished surface 9 shown in dotted line.The tool IA is shaped to have a round nosed cutting edge and a finishingedge 1B; the latter for finishing the surface IDA into the final surfaceID. The spacing of the tools I, IA is such that the tool I will run onfrom the finished surface I I before the cutting edge 13 reaches andfinishes the shoulder surface III. The adjustment 3| is initially so setas to stop travel of the slide 29 along the ways 30 just as the cuttingsurface 1B reaches the desired finish line I ll. Thereafter continuedrotation of the workpiece 6 win mean that the tool I is cutting air atthe left beyond the finished surface II and the tool IA repeats its pathalong the finished surface I0, 9.

It will be apparent that while I have illustrated and described myinvention in connection with a vertical boring mill, it is not limitedthereto, and that there are many other types of material shaping orforming machines to which the invention may be adapted. Further featuresand advantages, beyond those here described, will be apparent to thoseskilled in the art.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In a vertical boring mill in combination, a stationary single pointcutting tool, a, work piece rotatable relative to the cutting tool,means for laterally moving the work piece relative to the cutting tool,a pattern having the desired shape of the work piece and rotated insynchronism with the work piece, a tracer laterally positioned with thework piece and scanning the pattern, said tracer controlling said means,and other means progressively laterally positioning the tracer relativeto the pattern.

2. The combination of claim 1 wherein said other means comprises ahydraulically actuated slide positionable along the lateral path ofmovement of the work piece.

3. The combination of claim 1 wherein said other means includes ahydraulic servo-motor, and variable speed control means for theservomotor providing a progressive uniform lateral movement of thetracer relative to the rotating pattern.

4. In a material forming machine in combination, a stationary singlepoint cutting tool, a work piece and work holder rotatable relative tothe cutting tool, a rotatable pattern having the desired shape or thework piece, means 1 tating the work piece and pattern in synchronism, atracer adapted to scan the rotating pattern, hydraulic means arranged toposition the work piece and tracer laterally in either direction along asingle path relative the tool and pattern respectively, the tracercontrolling thersaid hydraulic means, other hydraulic power meanslaterally positioned with said work piece and arranged to continuouslyurge the tracer in one direction laterally relative the patternirrespective of the positioning or the first hydraulic means, and meansregulating the extent or such ur n 5. The combination of claim 4 whereinsaid last means includes a valving control of fluid discharge from saidother hydraulic power means.

6. In a material forming machine in combinative the pattern, whereby inoperation the cutting tool will describe a repetitive path on the workpiece as dictated by the shape of the pattern, and other meanscontinuously urging the tracer in one direction relative the patternwhereby the cutting path will be progressively laterally moved on thework piece.

CLARENCE JOHNSON.

